In dealing with the universal and the particular he considers that the universal exists only in the human mind: the abstract idea of the genus is formed in the mind of the observer when he compares individuals and makes note of their points of similarity, but this abstract idea exists only as a mental concept and has no objective reality. The universal precedes the individual (genus ante res) only in the way that the general idea existed in the mind of the Creator before the individual was formed, just as the idea of an object to be made exists in the mind of the artificer before the work is executed. The general idea is realised in matter (genus in rebus), but only when accompanied by accidents: apart from these accidents it exists only as a mental abstraction. After the general idea is realised in matter (genus post res) it is possible for the intellect to make a mental abstraction and to use this as a standard of comparison with other individuals. The generic belongs only to the realm of thought, and such abstract ideas have no objective existence, although they may be used as real in logic. The soul is treated as a collection of faculties (_kowa_) or forces acting on the body: all activity of any sort, in bodies animal or vegetable, as well as human, proceeds either from such forces added to the body or from the mixture of elements from which the body is formed. The simplest soul condition is that of the vegetable whose activity is limited to nutrition and generation and accretion by growth (_Najat_, p. 43). The animal soul possesses the vegetable faculties but adds to them others, and the human soul adds yet others to these, and the addition made to the human soul enables it to be described as a rational soul. The faculties present in the soul may be divided into two classes, the faculties of perception and the faculties of action. The faculties of perception are partly external and partly internal: of these the external faculties exist in the body wherein the soul dwells and are the eight senses, sight, hearing, taste, smell, perception of heat and cold, perception of dry and moist, perception of resistance as by hard and soft, and perception of rough and smooth. By means of these senses the form of the external object is reproduced in the soul of the percipient. There are four internal faculties of perception: (i.) _al-musawira_, “the formative,” whereby the soul perceives the object without the aid of the senses as by an act of imagination; (ii.) _al-mufakkira_, “the cogitative,” by which the soul perceiving a number of qualities associated together abstracts one or more of them from the others with which they are associated, or groups together those which are not seen as connected; this is the faculty of abstraction which is employed in forming general ideas; (iii.) _al wahm_, or “opinion,” by means of which a general conclusion is drawn from a number of ideas grouped together; and (iv.) _al-hafiza_ or _az-zakira_, “memory,” which